1. Field of the Invention
The present invention relates generally to surgical instruments, and more particularly to a new and improved osteotome.
2. Description of the Prior Art
Many bone deformities in the human foot lend themselves to correction by means of surgical procedures. For example, in the instance of improper formation, angulation, or orientation of a particular bone with respect to other bones or components of the foot, the surgical procedure normally involves the removal of a wedge-shaped section of the malformed or misaligned bone at a predetermined location and the relative repositioning of the remaining bone sections so as to impart to the surgically corrected bone the proper relative configuration or orientation. The wedge-shaped section removed from the original bone is, of course, of a predetermined size which naturally depends upon the extent of the correction required.
It has been found that the formation of the wedge-shaped sections, in compliance with preoperative bio-geometric computations, has been difficult to implement as the same is normally based, in large part, upon the adroitness of the individual practitioner. As a result, unacceptable variances between the surgically corrected bone and the ideally corrected bone, as determined by means of the aforenoted pre-operative computations, sometimes occur. Such variations, of course, must then either be rectified or compensated for by means of additional operational procedures in order to achieve the ideally corrected bone structure, or alternatively, may simply be permitted to exist without any further modifications being implemented. Either course of action is deemed unacceptable and undesirable from the patient's viewpoint.
The formation of the aforenoted wedge-shaped bone sections, and the severance and removal thereof, is normally achieved by several well-known means, e.g. conventional power saws, burrs or osteotomes; however, each of these means has inherent disadvantages of operative drawbacks. All of such means exhibit the shortcoming of not being readily able to accurately reproduce the desired wedge-shaped bone section in accordance with pre-operative considerations, and in addition, it has also been found that power saws often generate excessive heat which deleteriously affects the bone.
Circular saws have also, in the past, been utilized to form circular or crescentric cuts 10 in the bone, as shown in FIG. 1; however, the operational drawback of such a procedure has been the absolute necessity for the relative fixation of the bone components, which is normally achieved through means of pins or screws, due to the inherent alignment or orientation instability in the lateral direction characteristic of such cuts. The employment of such cutting devices, and the creation of the aforenoted cutting patterns, also does not permit the bone sections to be accurately aligned or oriented with respect to one another in three orthogonal planes, or in other words, with six degrees of freedom. Still further, with the use of circular saws, the resulting kerf is often inaccurate. In instances where the overall length of the bone is critical, an inaccurate kerf can deleteriously affect the proper location or disposition and operative functioning of the bone.
With the utilization of the foregoing wedge-creation techniques, the instability problems characteristic of the circular or crescentric techniques are overcome. However, conventional wedge-creation techniques exhibit other formidable problems. As shown in FIG. 2, the wedge section 12 is adapted to be removed from the bone 14, and it is particularly noted that the transverse dimension of the wedge section 12 is less than that of bone 14 so as to define a bone section 16 which is intact and residually integral with upper and lower bone sections 18 and 20, respectively. In this manner, section 16 ideally serves, in effect, as a hinge mechanism, e.g. so as to permit upper bone section 18 to be moved in the clockwise direction whereby the severance surfaces 22 and 24, originally defining wedge section 12 which has now been removed, may be mated. In this manner, the space which housed wedge section 12 is able to be closed, and as a result, upper bone section 18 may be re-aligned or re-oriented with respect to lower bone section 20 so as to achieve the ideal bone configuration or orientation.
While the aforenoted wedge-section techniques appear practicable, in actuality residual bone section 16 is often inadvertently fractured. Such circumstances obviously present considerable problems to the surgeon during surgery as well as to the patient. Still further, in practicing such wedge-section techniques, the bone sections 18 and 20 must be relatively fixed with respect to each other, and such a fixation process involves a considerable expenditure of time, is quite tedious to accomplish and requires a great amount of skill on the part of the surgeon. More particularly, as seen in FIG. 2, the osteotomy site is provided with a plurality of bore holes 26 which are drilled through the bone 14 upon opposite sides of wedge section 12. Wires or clasps (not shown) are then inserted through the holes and are suitably secured therein.
The cuts defining wedge section 12 may be made by means of a planar, chisel-type osteotome which eliminates the risk of exposing the bone to excessive heat, as is characteristic of power saws, or alternatively, the same could also be accomplished through means of burrs. The latter, however, as in the instance of power saws, do create excessive heat which tends to burn the bone sections; in addition, burrs are relatively unreliable for producing accurate cuts. This is particularly true if the same encounter variants of osseous tissue, which causes the burrs to exhibit skip positioning characteristics, e.g. as a result of the wedge section being necessarily defined within the medullary canal section of the bone. The preferred area of the bone within which the wedge section is defined is thus seen to be the cancellous portion of the head or base of the bone. Lastly, it is also noted that in employing both planar osteotomes or burrs, the ideal and accurate positioning of the bone sections with six degrees of freedom is also not achieved.
Another prior art technique which seeks to correct foot bone deformities by means of surgical procedures employs an osteotome which is V-shaped in transverse cross-section. This device has been particularly useful in the treatment of IPKs (intractable plantar keratoses) of the lesser metatarsals and, as can been seen in FIG. 3, the osteotomy site extends the full width of the bone 14. While the cutting of the bone can be accomplished by means of suitable saws or burrs, the V-osteotome is faster, easier to manipulate and more accurate in its resulting cuttings as both legs of the V-shaped cut are severed at the same time so as to be defined at predetermined locations relative to one another.
While the V-shaped osteotome has thus found particularly widespread use in the flotation of the metatarsals, the use of such an instrument is nevertheless considerably limited because the bone sections 18 and 20 are fixed relative to one another in the lateral direction as a result of the interlocking V-sections of such bones. This inherent lateral stability thus prevents the bone sections from experiencing six degrees of freedom. In addition, there is no means providing for an accurate adjustment of the bone sections relative to one another when, for example, a portion similar to the aforenoted wedge-section, of one of the bone sections is to be removed so as to correct the foot bone deformity. Thus, the employment of such an osteotome does not prove beneficial in performing the type of surgery required to correct the bone deformities of the type described hereinabove and exemplified in FIG. 2.